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NEET 2015 (AIPMT, Cancelled Paper) · Applications of Bernoulli's Theorem

Applications of Bernoulli's Theorem question from NEET 2015 (AIPMT, Cancelled Paper)

Q8NEET 2015 · AIPMT · CANCELLED PAPERMedium

Applications of Bernoulli's Theorem

A wind with speed 40 m/s blows parallel to the roof of a house. The area of the roof is 250 m2. Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be (ρair=1.2 kg/m3)(\rho_{air} = 1.2\, kg/m^3)

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Answer: (a)

  1. Pressure above the roof is lower: ΔP=12ρv2=12(1.2)(40)2=960 Pa\Delta P = \frac{1}{2}\rho v^2 = \frac{1}{2}(1.2)(40)^2 = 960\text{ Pa}
  2. F=ΔP⋅A=960×250=2.4×105 NF = \Delta P \cdot A = 960 \times 250 = 2.4\times10^{5}\text{ N}
  3. Higher pressure is inside, so the force acts upwards.
  4. So the answer is (a) 2.4×1052.4\times10^{5} N, upwards.
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